Function emit_reference_link 

pub fn emit_reference_link(
    builder: &mut GreenNodeBuilder<'_>,
    link_text: &str,
    label: &str,
    is_shortcut: bool,
    config: &ParserOptions,
)

Emit a reference link node to the builder. Preserves the original reference syntax (explicit [text][ref], implicit [text][], or shortcut [text]).